The invention relates to a filter comprising a spirally wound filter medium formed from a corrugated filter layer and a flat filter sheet for separating particles from a fluid stream. In a preferred aspect the invention relates to a diesel particle filter for separating particles from the exhaust stream of an internal combustion engine.
Filters having a spirally wound filter medium are known in the art. The filter medium is formed from a corrugated filter layer and a flat filter sheet. The corrugated filter layer has corrugation valleys and peaks. To connect the filter layer to the filter sheet, the corrugation valleys are glued to the filter sheet. Thus, channels are formed between the corrugation peaks and the filter sheet. As the filter medium is wound, channels are also formed between the corrugation valleys and the filter sheet wound on top of them. The end faces of the channels are alternately closed, so that the fluid to be cleaned can flow into a channel, flow through the filter sheet or the filter layer and flow out of the filter through the adjacent channel. Adhesive is used to connect the corrugated filter layer to the filter sheet and close the end faces of the channels. When the corrugation valleys are connected to the filter sheet, the filtering surface is blocked by the adhesive applied. To alternately close the channels, adhesive is applied between the filter sheet and the filter layer. This adhesive fills the volume formed between the corrugation peaks and the filter sheet, which requires a large amount of adhesive.